U.S. Pat. No. 4,001,950 discloses a model for practising artificial respiration using the mouth-type resuscitation procedure, comprising a structure simulating at least the head, thorax and the lungs of a human being. The respiratory tract including the lungs is formed by a bag which is disposed within the thorax and which can be inflated against a resilient resistance. The bag is connected to the hollow cavity in the head by way of a duct which simulates the trachea. The part of the head structure which contains the mouth and/or nose openings is releasably connected to the remainder of the head and includes a connecting device for an inflatable balloon disposed in the interior of the head. A person using the model for practice purposes can inflate the balloon through the mouth/nose opening whereby air in the interior of the head is displaced into the simulated lungs, thereby simulating artificial respiration of a human being.
An important advantage of that arrangement is that the part of the respiratory tract which extends from the mouth/nose opening to the simulated lungs and which comes into contact with the exhaled air of the person practising the procedure and thus with the mouth of that person is replaceable. That therefore eliminates the risk of another person who subsequently uses the model for artificial respiration practice purposes suffering from infection due to viruses or bacteria which have remained on or in the model from the previous person using the model, because the replaceable part of the respiratory tract, namely the balloon, can be replaced, together with the mouth/nose part of the model. It is possibly only the balloon that is removed and thrown away because the mouth/nose portion can be cleaned and disinfected.
That model suffers from the disadvantage that it is relatively expensive to use for although the level of requirements made in respect of the replaceable balloon, from the point of view of the mechanical properties thereof, is low, the interior thereof must be physiologically satisfactorily clean and most preferably sterile as in the course of practising artificial respiration the content thereof will have a tendency to flow back to the person using the model for practising purposes, and can thus contaminate the mouth of that person. In particular however the mouth/nose portion of the model must comprise a physiologically acceptable material and must be sterile prior to use of the model. In addition it must be such that it can be air-tightly fitted into the head of the model, and that requires that part of the model to be of a precisely defined shape and to exhibit sufficient mechanical strength because otherwise the air which is displaced in the interior of the head by virtue of the balloon being inflated is not urged in its entirety into the simulated lungs but can escape from the head and thereby result in a false picture of the artificial respiration process. Those requirements in regard to the degree of precision in the shaping of the model and in regard to the quality of the material used as well as satisfactory fitting of the mouth/nose portion in the head of the model in conjunction with the balloons to be used therein increase the costs involved beyond a level which is generally considered to be acceptable for disposable components. If in addition consideration is given to the need for storage of adequate amounts of balloons as well as the replacement time required for replacing a used balloon by a fresh balloon, the result, as mentioned above, is a comparatively high level of overall costs which mean that instruction and practice in the mouth-type resuscitation procedure become an expensive matter.